Lifting sling devices are always used to transport patients or disabled people. The critical issue in using lifting sling devices is how to prevent accident and cross-infection between patients. The earliest lifting sling device is made of woven fabrics, which is not only expensive but also easy to lead to cross-infection. CN 1184628 has disclosed a disposable or limited lifting device (corresponding to the lifting sling device here) made of nonwoven fabrics. As nonwoven fabrics are a fraction of the cost of woven fabrics and have the same carrying ability, it is possible to make the lifting device dedicated so as to prevent the risk of cross-infection. However, a new problem is derived that how to deal with the discarded lifting device. It is common to embed or incinerate the discarded lifting device, but the gas produced from the incinerating process may pollute environment and the landfill may also damage environment when the lifting device is not biodegradable.
Among the common biodegradable polymers today, the advantage of the polylactic acid (PLA) as biodegradable/compostable polymer for plastics and fibers is that although it is derived from natural, renewable materials, it is also thermoplastic and can be melt extruded to produce plastic items, fibers and fabrics with good mechanical strength, toughness, and pliability comparable to similar materials produced from a wide range of oil-based synthetics such as polyolefins (polyethylene and polypropylene) and polyesters (polyethylene terephthalate and polybutylene terephthalate). PLA is made from lactic acid, a fermentation byproduct derived from corn (Zea mays), wheat (Triticum spp.), rice (Oryza sativa), or sugar beets (Beta vulgaris). When polymerized, the lactic acid forms an aliphatic polyester with the dimmer repeat unit shown below:

Poly(hydroxyalkonate)s [PHAs] have been found to be naturally synthesized by a variety of bacteria as an intracellular storage material of carbon and energy. The Co-polyester Repeat Unit of P(3HB-co-4HB) of P(3HB-co-4HB) is as follows:

Polybutylene adipate terephthalate (PBAT) is a biodegradable polymer which is not currently produced from a bacteria source, but is synthesized from oil-based products. Although PBAT has a melting point of 120° C., which is lower than PLA, it has higher flexibility, excellent impact strength, and good melt processibility. Even though PLA has good melt processing, strength, and biodegradation/composting properties, it has low flexibility and low impact strength. Blending PBAT with PLA improves the end-product flexibility, pliability and impact strength. The chemical structure of PBAT is shown below:

Poly(butylene succinate) (PBS) are synthesized by the polycondensation reactions of glycols. The chemical structure of PBS is shown below:
